This invention relates generally to sports racquets. More particularly, this invention relates to a sports racquet with undulations in the interior surface of the frame for increasing the overall strength, durability and stiffness of the racquet.
Racquets for sports such as tennis, racquetball, squash and badminton are well known in the art and by the public. Many currently existing racquets include a tubular frame made of a composite or other material which surrounds a string bed, with the string bed serving as the hitting surface for the racquet.
Although such racquets have many beneficial qualities, they also have drawbacks which this invention addresses. In the regions of the racquet frame in which the frame has a high degree of curvature, the material that exists on the outside of the frame will cover a greater distance than the material on the opposite or the inside of the frame. This can be seen in FIG. 1, wherein a standard racquetball racquet the length of the inner side of the racquet frame is significantly less than the length of the outer side of the racquet frame. This difference is most pronounced where the curvature of the racquet frame is the greatest. This difference in surface length causes the material on the inside of the frame to bunch or crease. This bunching or creasing, which is the unintended and random result of the manufacturing process, will cause wrinkles to form in materials on the inside of the frame, creating areas of weakness and undesired flexibility, as well as inconsistencies in strength and stiffness, in the frame. The creases, wrinkles or bunching that occurs in the inner side of the racquet can be seen in prior art FIGS. 2-3, which show a frame made out of laminations of fibrous material in a resin matrix, per conventional manufacture. As shown in these figures, creases, bunches or wrinkles 120 in the inner side 112 of a racquet frame 102 occur intermittently, causing various weak portions in the racquet frame. The resulting weaknesses, undesired flexibility, and inconsistencies in strength and stiffness, can affect the overall performance of the racquet and can also lead to a cracking or breaking of the racquet frame.
Therefore, it is desirable to develop a racquet frame that reduces or minimizes the incidence of bunches, creases and wrinkles formed on the inside of the racquet frame and proximate areas of curvature of the frame.
The invention provides for a sports racquet (such as ones used in squash, racquetball, badminton and tennis) including a handle and an elongated frame coupled to the handle. The frame includes a head portion, sometimes a shaft portion, and a throat portion, with the throat portion connecting the head portion to the shaft or handle. An inner side includes a plurality of undulations formed into the racquet that result in a varying frame cross section at different portions along the racquet frame. These undulations result in a longer inner side surface length, making the linear distance on the inner side of the frame more similar to the linear distance on the outer side of the frame for a particular frame segment. The undulations can be used continuously or intermittently inside the frame. A different number and variety of undulations can also be used. The undulations may be varied in frequency, height, length, depth, and shape. The present invention has application to racquets formed from any of a variety of materials including composites and metals.
It is therefore an advantage of the invention to provide a sports racquet that is formed so as to reduce or minimize the number of areas of weakness, undesired flexibility and inconsistencies in strength on the racquet frame.
It is as yet another advantage of the present invention to provide a sports racquet that has an increased overall strength in the racquet frame.
It is still another advantage of the present invention to provide a sports racquet that has a predictable level of strength and stiffness in the frame.
It is yet another advantage of the invention to provide a sports racquet wherein the frame has a more consistent weight and balance.
It is finally another advantage of the invention to provide a sports racquet that has an increased level of durability for a given amount of material and weight in the racquet frame.
Further advantages and features of the present invention will be apparent from the foregoing specification and claims once considered in connection with the accompanying drawings illustrating the preferred embodiment of the present invention.